Several years ago, a great friend of mine provided me with two Glock Extended Magazine releases for my Gen 3 G17 and G19. What I really wanted was the FBI one; AKA the Magazine Release Glock Allegedly Kiped From Larry Vickers (whether or not that's actually true, I don't know). However, those at the time I was in the hunt was pretty much unobtanium, so I went with the full-blown Glock Extended.
Mechanically, they worked just fine, and provided me with some nice stand-off distance from the receiver for my releasing finger to make it easiier to access and activate; and they're relatively sharp corners really didn't bother or affect me at all.
However, there were two downsides; 1), if you placed the gun release-side down on a flat, ungiving surface (like a nightstand table top) and inadvertantly pushed down, youi'd trigger the release; 2), Similarly, if you holstered the Glock with the Extended Release in a high-wall holster, where the release-side holster wall impacted on the release extension, it could inadvertantly activate the magazine release, and you'd be unknowingly have a single-shot pistol.
Obviously, there were some practical work-arounds: For nightstand use, I avoided the issue simply by propping the slide on an immovable raised object on the nightstand, which both pre-positioned the Glock for easier grabbing and kept the extended release out of trouble. And for carry, I simply judiciously chose appropriate holsters, ones that had cut-outs or no material around the magazinew release area that could impact on the magazine release.
However, I inevitably rigged up one day with a non-compliant holster, one that I am T&Eing. And I strolled out EDC'd. And when I got home, I discovered that the holster/release impact had indeed activated the release. The magazine was fractionally disengaged from the retaining catch-lowering the magazine sufficiently to preclude the slide feeder rail from stripping out and chambering cartridges from the magazine-and I was noncholantly strolling around with a single-shot pistol...
And while I liked the stand-off distance provided by the extended release, I literally can't recall a time where I fumbled to access or had any difficulties in activating the OEM release. It may take a slightly more forceful/deliberate effort, but that's simply not a big deal, and effort that I normally expend anyhow when activating a magazine release.
So-back to the OEM release on both the G17 and G19. And unless I choose or convert all my appropriate Glock holsters so that they can't inadvertantly impact on a magazine release, prudence dictated that where I'm at is where I'll stay (unless I dedicate any gun to being specifically a game gun, with a specific game holster-which I certainly don't see happening with the Glocks concerned.
So, not that the extended release is a Bad Thing per se, or that they (in my case, the Glock component) don't work and work effectively. But for me, they turned out to be not the best idea. YMMV. And I realize that if I really want a quality intermediate-length extended magazine release for my Glocks, there's the Vickers one, which my understanding is the same size as the FBI component; an intermediate between the Glock OEM and Extended length, with less chance of inadvertant release, but going that route would cast me out of SSP into ESP in IDPA. Not exactly the end of life as we know it, but for the time being I'll just stick with the Glock original component
Best, Jon